JPH018792Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an expansion pipe joint.

For example, in a nuclear reactor, a core water injection system is installed in preparation for the occurrence of a loss of coolant accident, and if cooling water in the core is lost, the system sprays cooling water directly onto the fuel assemblies. There is.

Water is supplied to the core water injection system through a low-pressure injection pipe, and as shown in FIG. It is interposed.

That is, this expansion joint 3 connects a flange pipe 5a disposed on the pressure vessel inner wall 1 side of the low-pressure water injection pipe and a flange pipe 5b disposed on the shroud 2 side to form a part of the low-pressure water injection pipe. This absorbs thermal expansion and contraction due to the temperature difference between the inside and outside of the flange pipes 5a and 5b.

FIG. 2 shows an example of such a conventionally used expansion pipe joint. tubes 5a and 6a
and ring-shaped clamps 7a and 7b that connect 5b and 6b, respectively, and a sleeve 8 and bellows 9 that connect both flange pipes 6a and 6b, and one end of the bellows 9 is connected to a flange pipe. Covers 10a, 10 fixed to 6a, 6b
b is installed.

The outer circumferential surface near both ends of the sleeve 8 is processed to have a semicircular cross section, so that when thermal expansion and contraction occurs in the pipe line or when a difference in thermal expansion occurs between the pressure vessel inner wall 1 and the shroud 2, the flange pipe It slides on the inner surfaces of 6a and 6b and absorbs thermal expansion and contraction.

In the figure, reference numeral 11 indicates a pin provided between the vicinity of one end of the sleeve 8 and the flange pipe 6a in order to prevent movement of the sleeve 8.

In the conventional expansion pipe joint configured in this way, there is some gap between the flange pipes 6a, 6b and the sleeve 8, but the leakage of hot water from the shroud 2 side and the leakage of hot water inside the pipe is prevented by the bellows 9. It is prevented by twisting.

However, both ends of bellows 9 and cover 1
Between 0a, 10b and flange pipes 6a, 6b,
Because these welds are individually welded, if leakage water accumulates in these welds, stress corrosion cracking may occur in the welds within a relatively short period of time.In order to prevent this, quality control of the welds is extremely important. It becomes a nuisance.

Further, covers 10a and 10b are fitted over the bellows 9 to reduce fluid resistance against the downcomer flow from the upper steam separator and water supply spargeer (not shown).
Since a predetermined gap is formed between b to absorb thermal expansion and contraction, the fluid resistance cannot be lowered sufficiently.

The present invention was developed in response to such conventional circumstances, and instead of the bellows used to prevent leakage of fluid in pipes, packing is attached to the sleeve to eliminate welds and prevent stress corrosion. The purpose of this project is to propose an expansion pipe joint that eliminates the risk of occurrence of downcomer flow, reduces fluid resistance to downcomer flow, and maintains the displacement absorption function and ease of replacement and maintenance that conventional types have. It is.

The details of the present invention will be described below with reference to embodiments shown in the drawings.

The expansion pipe joint shown in FIG. 3 includes a pair of first sleeves 13a, 13b connected to flanged pipes 12a, 12b, which are arranged coaxially and facing each other.
and ring-shaped clamps 16a, 16b with wedges 14, 15 inserted into the inner periphery recesses, which connect these flange pipes 12a, 12b and first sleeves 13a, 13b, respectively, and first sleeves 13a, 13b.
The main portion is constituted by a connecting sleeve 17 communicating therebetween.

Ring grooves 18a, 18b are provided on the outer periphery of the enlarged portion formed near both ends of the connection sleeve 17, and these grooves 18a, 18b have a first
Piston rings 19a, 19b having diameters matching the inner diameters of the sleeves 13a, 13b are attached.

Note that one end of the connection sleeve 17 is provided with a pin 20 as a fixing mechanism for regulating the movement of the connection sleeve 17.
is fixed to the first sleeve 13a.

In the expansion pipe joint configured in this way, when thermal expansion and contraction occurs in the flange pipes 12a and 12b, for example in the axial direction, the thermal expansion and contraction is completely absorbed by the relative movement between the connecting sleeve 17 and the first sleeve 13b. .

Moreover, between the first sleeves 13a, 13b and the connection sleeve 17, piston rings 19a, 19
Since the seal is completely sealed by b, the bellows 9 required in the conventional expansion pipe joint shown in Fig. 2 is completely sealed.
Also, the covers 10a and 10b can be removed, and as a result, the risk of stress corrosion cracking in the welded portion can be eliminated, and fluid resistance due to downcomer flow can be significantly reduced.

In the embodiment shown in FIG. 4, instead of fixing one end of the connecting sleeve 17 using the pin 20 as in the embodiment shown in FIG.
A fixing mechanism is employed in which the inner diameters of a and 21b are made smaller than the outer diameter of the connecting sleeve 22, and the axial movement of the connecting sleeve 22 is restricted within a predetermined range.

In addition, in FIG. 4, 23a and 23b indicate barrel face type piston rings.

In the expansion pipe joint configured in this way, one end of the connection sleeve 22 is connected to the flange pipe 1 by the pin 20.
Since there is no need to fix it to 3a, the assembly work of the expansion pipe joint can be made very easy.

The embodiment shown in FIG. 5 uses first sleeves 24a, 24b with threads cut on the inner surface in place of the clamps 16a, 16b of the embodiment shown in FIGS. 25 and flange pipes 26a, 26b.

That is, threads are formed on the outer peripheral surfaces of the flange pipes 26a and 26b, and the threaded sleeve 24
a and 24b are screwed together with this screw. Also,
The threaded portion is sealed with seal ring materials 27a and 27b.

Additionally, tapered face-shaped piston rings 29a, 29b are inserted into grooves 28a, 28b provided in the enlarged portions formed near both ends of the connection sleeve 25, respectively, and the connection sleeve 25 and the threaded first sleeves 24a, 24b are inserted. Prevents liquid leakage between. Also, the outer diameter of the connecting sleeve 25 is the same as that of the flange pipe 2.
It is formed to be larger than the inner diameter of the connecting sleeves 6a and 26b, and serves as a fixing mechanism that restricts movement of the connecting sleeve 25 in the axial direction.

In addition, the connection sleeve 25 and the flange pipe 26a,
A gap of several mm is formed between the pressure vessel inner wall 1 and the shroud 2 to absorb the difference in thermal expansion between the pressure vessel inner wall 1 and the shroud 2.

In the expansion pipe joint configured in this way, one end of the connection sleeve 25 is connected to the flange pipe 2 by the pin 20.
It is no longer necessary to fix to clamp 6a, and clamp 1
6a and 16b are no longer necessary, so the assembly work of the expansion pipe joint becomes easier than that of the expansion pipe joint shown in FIG.

Furthermore, in the expansion pipe joint configured in this way, by providing a groove or a hub on the outside of the first threaded sleeves 24a, 24b, the first sleeves 24a, 24b can be rotated by remote control, and the first sleeves 24a, 24b can be rotated by remote control. Since the entire connection sleeve 25 can be replaced, radiation exposure to workers during replacement can be reduced.

As described above, according to the expansion pipe joint of the present invention, it is possible to remove the bellows and cover, and as a result, the risk of stress corrosion cracking and fluid resistance due to downcomer flow can be significantly reduced.
Also, the structure can be simplified.

In addition, in the embodiment described above, an example was described in which the expansion pipe joint of the present invention was used to connect low-pressure water injection pipes, but the scope of use of the expansion pipe joint of the present invention is not limited to this. Of course.

Regarding the shape of the piston ring, in order to prevent leakage even if the sleeve swings, the shape of the piston ring may be a plain type as shown in Figure 3, a barrel face type as shown in Figure 4, or a tapered face type as shown in Figure 5. Various piston rings can be used, including combinations of shapes.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing the installation state of a conventional expansion pipe joint, Fig. 2 is a longitudinal cross-sectional view illustrating a conventional expansion pipe joint, and Figs. 3 to 5 respectively show the expansion pipe joint of the present invention. FIG. 3 is a longitudinal cross-sectional view showing an example. 12a, 12b, 26a, 26b...flange pipe, 16a, 16b...ring-shaped clamp, 1
7, 22, 25... Connection sleeve, 18a, 18
b, 28a, 28b... groove, 19a, 19b, 2
3a, 23b, 29a, 29b... Piston ring, 13a, 13b... First sleeve, 24a,
24b...first sleeve.

Claims (1)

[Scope of utility model registration request] A pair of flange pipes are arranged coaxially with their connection ends facing each other, a pair of first sleeves are detachably fixed to these flange pipes, and an annular groove is carved on the outer periphery of the enlarged portion formed near both ends. and a connecting sleeve that is fitted with an annular packing in the groove and is slidably inserted into the pair of first sleeves, and a fixing mechanism that restricts movement of the connecting sleeve in the axial direction. An expansion pipe joint for connecting a reactor pressure vessel and a shroud, characterized by: